The field of this invention is that of thermally responsive controls, particularly a control which regulates fluid flow in response to temperature changes and which also regulates an electrical circuit in response to the same changes in temperature.
Thermally responsive snap-acting thermostat metal discs have been used in a variety of automotive applications for performing various control functions in response to selected changes in engine temperature. In some applications for example the discs have been used to operate valves in vacuum lines, thereby to regulate the application of manifold vacuum for effecting distributor spark advance, exhaust gas recirculation or the like when engine temperature has reached a desired level. It is now proposed that various electronic controls utilizing microprocessors and the like be provided for regulating operation of automotive engines to achieve improved fuel economies and efficiencies. For this purpose it has been proposed that sensor means be arranged to provide inputs to the electronic controls representative of various engine operating parameters such as engine temperature. In this regard, it would be desirable to be able to use manifold vacuum for effecting distributor spark advance or the like at a selected engine temperature while also being able to simultaneously provide an electrical input to an electrical or electronic control means indicating that the spark advance or other event had occurred. It would also be desirable if the thermally responsive control means used for such multiple purposes were adapted to provide digital signal output to facilitate signal processing in the electronic control means, were adapted to be easily modified to operate at different selected temperatures, and were also adapted for low cost mass production to find wide application in engine control system for automobiles in all price categories.
It is an object of this invention to provide a novel and improved thermally responsive control; to provide a novel and improved thermally responsive fluid and electrical switch; to provide such a switch which is particularly adapted for regulating operation of vacuum means in an automotive engine control system while also regulating operation of electrical means in that control system; and to provide such a switch having a construction which is adapted to be mass produced at reasonable cost. It is also an object of this invention to provide such an automotive engine control system utilizing such a novel and improved thermally responsive fluid and electrical switch.